EP3558893A1 - Method for manufacturing a red ceramic material - Google Patents

Method for manufacturing a red ceramic material

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Publication number
EP3558893A1
EP3558893A1 EP17825576.6A EP17825576A EP3558893A1 EP 3558893 A1 EP3558893 A1 EP 3558893A1 EP 17825576 A EP17825576 A EP 17825576A EP 3558893 A1 EP3558893 A1 EP 3558893A1
Authority
EP
European Patent Office
Prior art keywords
sintering
temperature
mixture
ceramic
duration
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP17825576.6A
Other languages
German (de)
French (fr)
Other versions
EP3558893B1 (en
Inventor
Yannick BEYNET
Romain EPHERRE
Florence Ansart
Pascal Lenormand
Claude Estournes
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Centre National de la Recherche Scientifique CNRS
Universite Toulouse III Paul Sabatier
Norimat SAS
Original Assignee
Centre National de la Recherche Scientifique CNRS
Universite Toulouse III Paul Sabatier
Norimat SAS
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Publication date
Application filed by Centre National de la Recherche Scientifique CNRS, Universite Toulouse III Paul Sabatier, Norimat SAS filed Critical Centre National de la Recherche Scientifique CNRS
Publication of EP3558893A1 publication Critical patent/EP3558893A1/en
Application granted granted Critical
Publication of EP3558893B1 publication Critical patent/EP3558893B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
    • C04B35/111—Fine ceramics
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
    • C04B35/486—Fine ceramics
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
    • C04B2235/3229—Cerium oxides or oxide-forming salts thereof
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/44—Metal salt constituents or additives chosen for the nature of the anions, e.g. hydrides or acetylacetonate
    • C04B2235/446—Sulfides, tellurides or selenides
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/66—Specific sintering techniques, e.g. centrifugal sintering
    • C04B2235/666—Applying a current during sintering, e.g. plasma sintering [SPS], electrical resistance heating or pulse electric current sintering [PECS]
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/9646—Optical properties
    • C04B2235/9661—Colour

Definitions

  • the present invention applies to the field of ceramic materials. More particularly, the present invention applies to the field of methods for producing ceramic materials.
  • the present invention relates to a method of manufacturing a red ceramic material.
  • the invention also relates to a ceramic material that can be obtained by said process as well as clock, jewelery or jewelery products comprising such a ceramic material.
  • Electric field assisted sintering techniques are well known for the densification and assembly of new nanostructured polymers, metals and ceramics and nanocomposites.
  • One of these techniques called “spark plasma sintering" (SPS) in English terminology, the most widespread in the world, is similar to conventional hot pressing, but it has the particularity to use series of high intensity electric current pulses for generating the heating of generally electrically conductive tools (eg graphite, carbide, steel, etc.) applying a uniaxial pressure on a sample to be densified placed in said tooling.
  • This current allows the heating of the sample by Joule effect.
  • Either the sample is conductive and the current passes through the sample, which leads to its direct heating.
  • Either the sample is insulating and the current then passes through a conductive graphite matrix in which the sample is first placed, which in turn heats the sample by conduction.
  • a typical flash sintering apparatus conventionally comprises a sintering chamber which is generally under vacuum (a few Pascals), two electrodes between which is inserted a generally graphite column containing the tools and which jointly make it possible to apply the electric current and the pressure. uniaxial to the sample through the tools.
  • the tools are made of a refractory material and conductor of electricity, this material preferably has a coefficient of expansion less than that of the material that is sought to obtain by flash sintering.
  • the tooling has internal walls delimiting a cavity of complementary shape to that of the part to be made of material thus manufactured.
  • ceramic materials are often used.
  • some watches have a ceramic material case or another part such as the middle part, the bottom, the bezel, the insert, the crown, the bracelet, etc.
  • Such ceramic materials need to possess high mechanical strength, low density (lightness), high hardness, high rigidity, high resistance to wear, cracking, heat and chemical agents, but also to be inert and hypoallergenic.
  • WO201 1 120181 discloses an opaque alumina-based ceramic, similar to ruby, and having high toughness enabling it to be used in watchmaking, jewelery and jewelery, and which comprises at least one metal oxide and at least one oxide of a rare earth element.
  • This application also discloses a method of manufacturing this ceramic using a step of sintering a mixture of powders comprising an alumina powder, at least one metal oxide and at least one oxide of a rare earth element.
  • the present invention aims to provide such a method, easy and fast, to obtain a product of ceramic material red homogeneous color.
  • the present invention is directed to a method of manufacturing a ceramic material which comprises the following steps of:
  • the cerium sulphide pigment resists, that is to say, it does not degrade, when it is subjected to heating at a temperature between 950 ° C and 1150 ° C be empty, this heating being achieved by the particular technique of sintering flash, i.e.
  • step b1 / the heating is carried out by pulses of electric current.
  • vacuum is meant for flash sintering, that the enclosure in which said sintering is carried out is under reduced pressure, that is to say a pressure more precisely between 2 and 50 Pa, preferably between 10 and 30 Pa. .
  • the adjustment of the sintering conditions falls within the skill of those skilled in the art who know perfectly, depending on the ceramic material used, to determine the operating conditions, in particular the temperature, the duration, the compression, the intensity of the pulsed current, etc., to obtain the desired final densification.
  • the invention also fulfills the following characteristics, implemented separately or in each of their technically operating combinations.
  • the flash sintering is carried out until the densification of the homogeneous powder mixture is between 90% and 100%, preferably between 95% and 100%, more preferably greater than or equal to 98%.
  • the b / sintering flash step comprises the application on said homogeneous powders mixture of a so-called sintering uniaxial pressure of between 25 and 130 MPa, preferably between 50 and 100 MPa.
  • the process comprises before and / or during the prior step bV, a uniaxial pressure increase phase applied to said homogeneous powders mixture of a duration t p up to the uniaxial pressure of sintering.
  • the process may comprise a uniaxial pressure rise phase of a duration t p of one minute at a temperature of 50 ° C., up to the uniaxial sintering pressure.
  • the sintering temperature is between 1000 ° C. and 1050 ° C.
  • the sintering temperature is maintained for a third time t 3 of between one and ten minutes.
  • the process comprises, after step b / of sintering, a phase of descent in temperature and uniaxial pressure for a fourth time t 4 , up to room temperature and zero uniaxial pressure.
  • the duration t 4 is between one and ten minutes. Preferably, it is five minutes. The descent in temperature and uniaxial pressure of such a fourth time t 4 is recommended to accommodate the stresses in the ceramic and thus limit the risk of cracking.
  • the first duration ti is between five and ten minutes
  • the second duration t 2 is between one and three minutes.
  • the first duration ti is nine minutes
  • the second duration t 2 is two minutes
  • the sintering temperature is 1050 ° C
  • the uniaxial sintering pressure is 100 MPa
  • the third duration t 3 is five minutes.
  • the first speed A is greater than 10 ° C / min and less than or equal to 200 ⁇ / ⁇ , preferably greater than 50 ° C / min and less than or equal to 150 ⁇ / ⁇ , more preferably greater than 90 ° C / min and less than or equal to 120 ° C / min.
  • the second speed B is greater than or equal to 10 ° C / min and less than 200 ° C / min, preferably Eiior or equal to 50 ° C / min and less than 150 ° C / min, more preferably greater than or equal to 90 ° C / min and less than 120 ° C / min.
  • the first speed A is 100 ° C / min and the second speed B is 50 ° C / min.
  • the ceramic is selected from zirconia, alumina and a mixture of zirconia and alumina.
  • the ceramic is zirconia reinforced with alumina (ATZ or "Alumina Toughened Zirconia" in English terminology).
  • the powder mixture comprises a weight percentage of cerium sulphide pigment of between 1% and 20%, preferably between 5% and 20%.
  • the powder mixture comprises a mass percentage of cerium sulphide pigment equal to 5%, 10% or 20%.
  • sinter additions such as Al 2 O 3 , TiO 2 , Y 2 O 3 , MgO, CaO, CeO 2 , etc., are added to the powders during step a / of mixture for improving the sinterability of the powder mixture and / or the mechanical properties of the ceramic material product obtained by the process object of the present invention.
  • the present invention aims at a homogeneous red-colored ceramic material obtained by the method which is the subject of the present invention, said ceramic material comprising a ceramic chosen from zirconia, alumina and a mixture of zirconia and alumina.
  • the colorimetry of the ceramic material being between 30 and 65 for the parameter L, preferably between 30 and 60 for the parameter L, between 10 and 40 for the parameter a, and between 0 and 35 for the parameter b, preferably between 0 and 20 for the parameter b, according to the system L * a * b * of the International Commission on Illumination, the hardness of the ceramic material being between 1000 and 1500 Hv, preferably between 1200 and 1500 Hv, and the toughness of the ceramic material being between 4 and 10 MPa.m 1/2 .
  • the present invention relates to a product of the field of jewelery, watchmaking or jewelery, comprising a homogeneous red-colored ceramic material obtained by a method that is the subject of the present invention.
  • FIG. 1 Variation of the temperature parameter (1 A) and of the uniaxial pressure parameter (1 B) in time according to an embodiment of the method which is the subject of the invention.
  • FIG. 2 Image visualized by an electron scanning microscope (SEM) of a red ceramic material based on zirconia obtained by an embodiment of the method that is the subject of the present invention.
  • SEM electron scanning microscope
  • FIG. 3 Evolution curves of the value of the parameters L * , a * and b * of the ceramic material obtained by the process of the present invention implemented with zirconia, specular reflection included (SCI or "Specular Component Included”) "In English terminology), according to the colorimetric system of the International Commission on Illumination, as a function of the mass percentage of cerium sulphide pigment present in the homogeneous powder mixture.
  • FIG. 4 SEM visualized image of a ceramic material based on ATZ obtained by an embodiment of the method that is the subject of the present invention. Detailed description of the invention
  • the present invention aims according to a first aspect a method of manufacturing a ceramic material product comprising the following steps of:
  • b / - flash sintering by electric current pulse heating of the homogeneous powder mixture under vacuum to densify said mixture, said sintering being carried out at a predetermined sintering temperature of between 950 ° C. and 1150 ° C. and having a prior step bi / heating said homogeneous powder mixture according to a temperature profile comprising:
  • the powder mixture should be homogeneous, that is, the grain distribution of Cerium Sulfide pigment powder among the ceramic powder grains should be homogeneous. Such homogeneity of the mixture may for example be obtained by the implementation of step a / of mixing the ceramic powder with the sulphide pigment powder. Cerium for a period of at least two hours.
  • the mixture can be made dry in a mixer such as a Turbula®, wet attrition or chemical.
  • Step b / flash sintering comprises applying to said homogeneous powder mixture a uniaxial pressure called sintering predetermined.
  • the flash sintering step b / of the powder mixture is at a uniaxial sintering pressure of 100 MPa (FIG. 1B) and a sintering temperature of 1050 ° C. (FIG. 1 A).
  • the process comprises before and / or during the prior step bi /, a uniaxial pressure increase phase on the homogeneous powders mixture with a duration t p of one minute up to the uniaxial sintering pressure 100 MPa.
  • This uniaxial pressure increase is carried out at a temperature of 50 ° C. in this embodiment.
  • a first phase of temperature rise effected by pulses of electric current is also observed at a first speed A of 100 ° C./min for a first duration ti of nine minutes, and a second phase.
  • temperature rise effected by pulses of electric current at a second speed B of 50 ° C / min for a second period of two minutes.
  • the sintering temperature of 1050 ° C is reached in second phase fn and is maintained for a third time t 3 for five minutes.
  • the uniaxial sintering pressure of 100 MPa is applied and maintained during the first, second and third periods t- ⁇ , t 2 and t 3 , that is to say during the flash sintering comprising the duration t 3 , but also during the prior step bi / comprising the durations t 1 and t 2 .
  • the uniaxial sintering pressure is applied and maintained only during the time t 3 , i.e. only during flash sintering but not during the prior step bi /.
  • the method also includes after step b / flash sintering, a temperature descent phase and uniaxial pressure for a fourth time t 4 for five minutes to room temperature and zero uniaxial pressure.
  • the equipment used for the flash sintering is a flash sintering apparatus commonly used, comprising a sintering chamber which is under vacuum, two electrodes between which is inserted a graphite column containing the tools, said electrodes for applying an electric current. and the pistons a uniaxial pressure, to the sample of powder mixture via the tools. Since flash sintering is well known to those skilled in the art, it is obvious to the skilled person that the sets of electric current pulses are series of pulses of direct electric current.
  • the tools are made of a refractory material and conductor of the electric current, this material having a coefficient of expansion less than that of the ceramic material that is sought to obtain by flash sintering.
  • the tools also have internal walls delimiting a cavity of complementary shape to that of the part to be made of ceramic material.
  • Example 1 Manufacture of a red ceramic material based on zirconia.
  • the ceramic powder used is zirconia powder TZ3Y (stabilized zirconia 3% molar yttrine).
  • the grain size of the ceramic powder is 63 ⁇ 8 nm.
  • the grain size of the cerium sulphide powder is about 200 nm ⁇ 24 nm.
  • TZ3Y (control) Zirconia TZ3Y + 0% by weight of pigment Ce 2 S 3 ;
  • TZ3Y5 Zirconia TZ3Y + 5% by weight of Ce 2 S 3 pigment
  • TZ3Y10 Zirconia TZ3Y + 10% by mass of pigment Ce 2 S 3 ;
  • - TZ3Y20 Zirconia TZ3Y + 20% by mass of Ce 2 S 3 pigment.
  • each of the powder mixtures is placed separately in a graphite matrix lined with a flexible graphite sheet (for example of the Papyex® type from the manufacturer MERSEN) to ensure electrical contact during flash sintering.
  • a flexible graphite sheet for example of the Papyex® type from the manufacturer MERSEN
  • graphite is deposited in the form of a spray at the interface between the pistons and the powder mixtures.
  • the objective is to protect the tools while limiting the reactions with the powder mixture.
  • This spray can be based on boron nitride.
  • Each graphite matrix comprising a mixture of powders is placed in the flash sintering apparatus and the densification by flash sintering is carried out according to the operating conditions shown in FIG. 1:
  • a first temperature increase phase is carried out at a first speed A of 100 ° C./min for a first duration 3 ⁇ 4 of nine minutes, and a second phase of temperature rise is carried out at a temperature of second speed B of 50 ° C / min for a second duration t 2 of two minutes;
  • the sintering temperature of 1050 ° C is reached at the end of the second phase and is maintained for a third time t 3 of five minutes;
  • FIG. 2 illustrates an image visualized with a scanning electron microscope of the red ceramic material resulting from the TZ3Y10 mixture.
  • Table 1 Evolution of the grain size after flash sintering for the mixture of powders TZ3Y10.
  • Density analyzes by the Archimedes method using a hydrostatic balance, Vickers hardness, and Vickers micro-indentation toughness have shown that the ceramic materials obtained according to the method of the present invention has a densification ratio greater than or equal to 98%, a hardness of between 1220 and 1490 Hv, and a toughness of between 4.5 and 6.8 MPa.m 1/2 (Table 2).
  • Example 2 Manufacture of a red ceramic material based on zirconia reinforced with alumina.
  • the ceramic powder used is alumina-reinforced zirconia powder (ATZ-20/80, 150 nm alpha alumina / 20 nm stabilized zirconia 2.5 mol%).
  • the grain size of the ceramic powder is between 80 ⁇ and 100 ⁇ .
  • the grain size of the cerium sulphide powder is about 200 nm ⁇ 24 nm.
  • ATZ (control) ATZ + 0% by weight of pigment Ce 2 S 3 ;
  • ATZ10 ATZ + 10% by weight of Ce 2 S 3 pigment
  • each of the powder mixtures is placed separately in a graphite matrix lined with a flexible graphite sheet (for example of the Papyex® type from the manufacturer MERSEN) to ensure electrical contact during flash sintering.
  • a flexible graphite sheet for example of the Papyex® type from the manufacturer MERSEN
  • Each graphite matrix comprising a mixture of powders is placed in the flash sintering apparatus and the densification by flash sintering is carried out under the operating conditions described in FIG. 1 and cited in example 1.
  • FIG. 4 illustrates a scanned electron microscope image of the red ceramic material from the ATZ10 mixture.
  • Table 3 Evolution of the grain size after flash sintering for the mixture of ATZ10 powders.
  • Example 3 Manufacture of a red ceramic material based on alumina.
  • the ceramic powder used is alumina powder whose grain size is about 150 nm.
  • the grain size of the Cerium Sulfide powder is about
  • AA10 Alumina + 10% by weight of Ce 2 S 3 pigment
  • - AA20 Alumina + 20% by weight of pigment Ce 2 S 3 ;
  • each mixture is added 15 g of attrition beads.
  • Each powder mixture is then placed in a Turbula® type mixer to be mixed for two hours without addition of binder or other organic compounds.
  • each of the powder mixtures is placed separately in a graphite matrix lined with a flexible graphite sheet (for example of Papyex® type MERSEN manufacturer) to ensure the electrical contact during flash sintering.
  • Graphite is also deposited as a spray at the interface between the pistons and the powder mixtures.
  • Each graphite matrix comprising a mixture of powders is placed in the flash sintering apparatus and flash sintering is carried out under the operating conditions described in FIG. 1 and cited in example 1.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Composite Materials (AREA)
  • Adornments (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Abstract

The present invention relates to a method for manufacturing a product in ceramic material, characterised in that it includes the following steps of: a/ mixing a ceramic powder with a powder of cerium sulphide pigment so as to obtain a homogeneous mixture of powders; and b/ flash sintering by heating the homogeneous mixture of powders via electric current pulses in a vacuum in order to densify said mixture, said sintering being carried out at a so-called predetermined sintering temperature of 950 °C to 1150 °C; said method comprising an intermediate step b1/ of heating said homogeneous mixture of powders according to a temperature profile comprising a first phase of increasing the temperature at a first rate A during a first time t1, and a second phase of increasing the temperature at a second rate B lower than the first rate A during a second time t2, until reaching the sintering temperature, which is then maintained during a time t3.

Description

Procédé de fabrication d'un matériau céramique de couleur rouge Domaine de l'invention  Process for producing a red colored ceramic material Field of the invention
La présente invention s'applique au domaine des matériaux céramiques. Plus particulièrement, la présente invention s'applique au domaine des méthodes pour la réalisation de matériaux céramiques.  The present invention applies to the field of ceramic materials. More particularly, the present invention applies to the field of methods for producing ceramic materials.
La présente invention vise un procédé de fabrication d'un matériau céramique de couleur rouge. L'invention vise également un matériau céramique susceptible d'être obtenu par ledit procédé ainsi que des produits d'horlogerie, de bijouterie ou de joaillerie comprenant un tel matériau céramique.  The present invention relates to a method of manufacturing a red ceramic material. The invention also relates to a ceramic material that can be obtained by said process as well as clock, jewelery or jewelery products comprising such a ceramic material.
Etat de l'art State of the art
Parmi les procédés de fabrication de matériaux céramiques, il est connu aujourd'hui d'utiliser des procédés de frittage de poudre.  Among the processes for manufacturing ceramic materials, it is known today to use powder sintering processes.
Les techniques de frittage assisté sous champ électrique sont bien connues pour la densification et l'assemblage des nouveaux matériaux polymères, métaux et céramiques nanostructurés et nanocomposites. L'une de ces techniques appelée frittage flash ou « spark Plasma Sintering » (SPS) en terminologie anglo-saxone, la plus répandue de par le monde, s'apparente au pressage à chaud conventionnel, mais elle a la particularité d'utiliser des séries d'impulsions de courant électrique de forte intensité pour générer la chauffe d'outillages généralement conducteurs d'électricité (ex graphite, carbure, acier ...) appliquant une pression uniaxiale sur un échantillon à densifier placé dans ledit outillage. L'application de ce courant permet le chauffage de l'échantillon par effet Joule. Soit l'échantillon est conducteur et le courant passe par l'échantillon, ce qui conduit à son chauffage direct. Soit l'échantillon est isolant et le courant passe alors par une matrice en graphite conductrice dans laquelle est au préalable placé l'échantillon, qui chauffe à son tour l'échantillon par conduction.  Electric field assisted sintering techniques are well known for the densification and assembly of new nanostructured polymers, metals and ceramics and nanocomposites. One of these techniques, called "spark plasma sintering" (SPS) in English terminology, the most widespread in the world, is similar to conventional hot pressing, but it has the particularity to use series of high intensity electric current pulses for generating the heating of generally electrically conductive tools (eg graphite, carbide, steel, etc.) applying a uniaxial pressure on a sample to be densified placed in said tooling. The application of this current allows the heating of the sample by Joule effect. Either the sample is conductive and the current passes through the sample, which leads to its direct heating. Either the sample is insulating and the current then passes through a conductive graphite matrix in which the sample is first placed, which in turn heats the sample by conduction.
L'intérêt de cette technique est qu'elle permet de densifier les matériaux très rapidement en quelques dizaines de minutes. Un appareil typique de frittage flash comprend classiquement une enceinte de frittage qui est en général sous vide (quelques Pascals), deux électrodes entre lesquelles est insérée une colonne généralement en graphite contenant les outillages et qui permettent conjointement d'appliquer le courant électrique et la pression uniaxiale à l'échantillon par l'intermédiaire des outillages. Les outillages sont réalisés en un matériau réfractaire et conducteur de l'électricité, ce matériau a de préférence un coefficient de dilatation inférieur à celui du matériau que l'on cherche à obtenir par frittage flash. L'outillage a des parois internes délimitant une cavité de forme complémentaire de celle de la pièce à réaliser en matériau ainsi fabriqué. The advantage of this technique is that it densifies the materials very quickly in a few tens of minutes. A typical flash sintering apparatus conventionally comprises a sintering chamber which is generally under vacuum (a few Pascals), two electrodes between which is inserted a generally graphite column containing the tools and which jointly make it possible to apply the electric current and the pressure. uniaxial to the sample through the tools. The tools are made of a refractory material and conductor of electricity, this material preferably has a coefficient of expansion less than that of the material that is sought to obtain by flash sintering. The tooling has internal walls delimiting a cavity of complementary shape to that of the part to be made of material thus manufactured.
Dans les domaines de la bijouterie, de l'horlogerie et de la joaillerie, il est souvent utilisé des matériaux céramiques. Par exemple, certaines montres comportent un boîtier en matériau céramique ou bien une autre partie telle que la carrure, le fond, la lunette, l'insert, la couronne, le bracelet, etc. De tels matériaux céramiques ont besoin de posséder une grande résistance mécanique, une faible densité (légèreté), une forte dureté, une grande rigidité, une résistance élevée à l'usure, à la fissuration, à la chaleur et aux agents chimiques, mais aussi d'être inerte et hypoallergéniques.  In the fields of jewelery, watchmaking and jewelery, ceramic materials are often used. For example, some watches have a ceramic material case or another part such as the middle part, the bottom, the bezel, the insert, the crown, the bracelet, etc. Such ceramic materials need to possess high mechanical strength, low density (lightness), high hardness, high rigidity, high resistance to wear, cracking, heat and chemical agents, but also to be inert and hypoallergenic.
La plupart des pièces céramiques mises en œuvre aujourd'hui sont de couleur noire, blanche, bleue ou encore marron. Pour des raisons esthétiques, il serait intéressant de pouvoir disposer de matériaux céramiques de couleur rouge homogène.  Most of the ceramic pieces used today are black, white, blue or brown. For aesthetic reasons, it would be interesting to have ceramic materials of homogeneous red color.
La demande WO201 1 120181 divulgue une céramique opaque à base d'alumine, similaire à du rubis et ayant ténacité élevée lui permettant d'être utilisée dans l'horlogerie, la bijouterie et la joaillerie, et qui comprend au moins un oxyde de métal et au moins un oxyde d'un élément du groupe des terres rares. Cette demande divulgue également un procédé de fabrication de cette céramique utilisant une étape de frittage d'un mélange de poudres comprenant une poudre d'alumine, au moins un oxyde de métal et au moins un oxyde d'un élément du groupe des terres rares.  WO201 1 120181 discloses an opaque alumina-based ceramic, similar to ruby, and having high toughness enabling it to be used in watchmaking, jewelery and jewelery, and which comprises at least one metal oxide and at least one oxide of a rare earth element. This application also discloses a method of manufacturing this ceramic using a step of sintering a mixture of powders comprising an alumina powder, at least one metal oxide and at least one oxide of a rare earth element.
Or, aujourd'hui il n'est pas connu de l'art antérieur de procédé rapide permettant d'obtenir de façon contrôlée des matériaux céramiques de couleur rouge homogène à base de sulfure de cérium et ayant des propriétés de dureté compatibles avec leur utilisation dans des domaines tels que ceux de la bijouterie, de l'horlogerie et de la joaillerie. However, today it is not known from the prior art of rapid process for obtaining in a controlled manner colored ceramic materials. homogeneous red based on cerium sulphide and having hardness properties compatible with their use in fields such as jewelery, watchmaking and jewelery.
La présente invention vise à proposer un tel procédé, facile et rapide, permettant d'obtenir un produit en matériau céramique de couleur rouge homogène.  The present invention aims to provide such a method, easy and fast, to obtain a product of ceramic material red homogeneous color.
Exposé de l'invention Presentation of the invention
À cet effet, selon un premier aspect, la présente invention vise un procédé de fabrication d'un matériau céramique qui comporte les étapes suivantes de :  For this purpose, according to a first aspect, the present invention is directed to a method of manufacturing a ceramic material which comprises the following steps of:
a/- mélange d'une poudre céramique avec une poudre de pigment Sulfure de Cérium de sorte à obtenir un mélange de poudres homogène ;  a / - mixing a ceramic powder with a powder of cerium sulphide pigment so as to obtain a homogeneous powder mixture;
b/- frittage flash par chauffage par impulsions de courant électrique du mélange de poudres homogène sous vide pour densifier ledit mélange, ledit frittage flash étant réalisé à une température dite de frittage prédéterminée comprise entre 950 °C et 1 150°C et comportant une étape préalable b de chauffage dudit mélange de poudres homogène suivant un profil de température comprenant :  b / - flash sintering by electric current pulse heating of the homogeneous powder mixture under vacuum to densify said mixture, said flash sintering being carried out at a predetermined sintering temperature of between 950 ° C. and 1150 ° C. and comprising a step prior to heating said homogeneous powder mixture according to a temperature profile comprising:
o une première phase de montée en température à une première vitesse A pendant une première durée t-i , o et une deuxième phase de montée en température à une deuxième vitesse B inférieure à la première vitesse A pendant une deuxième durée t2, jusqu'à atteindre la température de frittage. o a first phase of temperature rise at a first speed A during a first duration ti, o and a second phase of temperature rise at a second speed B lower than the first speed A for a second duration t 2 , until reaching the sintering temperature.
De manière tout à fait avantageuse, il a été constaté par les présents inventeurs qu'un tel procédé permet d'obtenir un matériau céramique de couleur rouge homogène, dénué en particulier de tâches sombres nuisant à son aspect esthétique. Il permet en outre de contrôler avec précision la colorimétrie du matériau céramique formé. Les inventeurs ont en particulier constaté que de manière tout à fait surprenante, le pigment sulfure de cérium résiste, c'est-à-dire qu'il ne se dégrade pas, lorsqu'il est soumis à chauffage à une température comprise entre 950 ° C et 1 150 ° C sois vide, ce chauffage étant réalisé par la technique particulière de frittage flash, c'est-à-dire par des séries d'impulsions de courant électrique et ledit frittage comprenant en outre une étape préalable b-i/ de chauffage dudit mélange de poudres homogène suivant un profil de température à deux phases comme décrit ci-dessus. Ceci est d'autant plus surprenant que l'art antérieur connu de l'homme du métier montre que le pigment de sulfure de cérium s'oxyde et se dégrade lorsqu'il est chauffé à plus de 350 °C par les techniques de chauffage autres. In a very advantageous manner, it has been found by the present inventors that such a process makes it possible to obtain a homogeneous red colored ceramic material, in particular devoid of dark spots detrimental to its aesthetic appearance. It also makes it possible to precisely control the colorimetry of the ceramic material formed. The inventors have in particular found that, quite surprisingly, the cerium sulphide pigment resists, that is to say, it does not degrade, when it is subjected to heating at a temperature between 950 ° C and 1150 ° C be empty, this heating being achieved by the particular technique of sintering flash, i.e. by series of pulses of electric current and said sintering further comprising a prior step bi / heating said homogeneous powder mixture according to a two-phase temperature profile as described above. This is all the more surprising since the prior art known to those skilled in the art shows that the cerium sulphide pigment oxidizes and degrades when it is heated to more than 350 ° C. by other heating techniques. .
Bien entendu, lors de l'étape b1 / le chauffage est réalisé par impulsions de courant électrique.  Of course, during step b1 / the heating is carried out by pulses of electric current.
On entend par « sous vide » pour le frittage flash, que l'enceinte dans laquelle est effectué ledit frittage est sous pression réduite, c'est-à-dire une pression plus précisément comprise entre 2 et 50 Pa préférentiellement entre 10 et 30 Pa.  By "vacuum" is meant for flash sintering, that the enclosure in which said sintering is carried out is under reduced pressure, that is to say a pressure more precisely between 2 and 50 Pa, preferably between 10 and 30 Pa. .
Le réglage des conditions de frittage entre dans les compétences de l'homme du métier qui sait parfaitement, en fonction du matériau céramique mis en œuvre, en déterminer les conditions opératoires, en particulier la température, la durée, la compression, l'intensité du courant puisé, etc., pour obtenir la densification finale souhaitée.  The adjustment of the sintering conditions falls within the skill of those skilled in the art who know perfectly, depending on the ceramic material used, to determine the operating conditions, in particular the temperature, the duration, the compression, the intensity of the pulsed current, etc., to obtain the desired final densification.
Suivant des modes de mise en œuvre préférés, l'invention répond en outre aux caractéristiques suivantes, mises en œuvre séparément ou en chacune de leurs combinaisons techniquement opérantes.  According to preferred embodiments, the invention also fulfills the following characteristics, implemented separately or in each of their technically operating combinations.
Dans un mode de réalisation, le frittage flash est réalisé jusqu'à obtenir une densification du mélange de poudres homogène comprise entre 90% et 100%, de préférence entre 95% et 100%, encore préférentiellement supérieure ou égale à 98%.  In one embodiment, the flash sintering is carried out until the densification of the homogeneous powder mixture is between 90% and 100%, preferably between 95% and 100%, more preferably greater than or equal to 98%.
Dans un mode de mise en œuvre particulier, l'étape b/ de frittage flash comprend l'application sur ledit mélange de poudres homogène d'une pression uniaxiale dite de frittage comprise entre 25 et 130 MPa, de préférence entre 50 et 100 MPa. Dans un mode de mise en œuvre particulier, le procédé comprend avant et/ou pendant l'étape préalable bV, une phase de montée en pression uniaxiale appliquée sur ledit mélange de poudres homogène d'une durée tp jusqu'à la pression uniaxiale de frittage. Par exemple, avant la première phase de montée en température, le procédé peut comprendre une phase de montée en pression uniaxiale d'une durée tp d'une minute à une température de 50° C, jusqu'à la pression uniaxiale de frittage. In a particular mode of implementation, the b / sintering flash step comprises the application on said homogeneous powders mixture of a so-called sintering uniaxial pressure of between 25 and 130 MPa, preferably between 50 and 100 MPa. In a particular embodiment, the process comprises before and / or during the prior step bV, a uniaxial pressure increase phase applied to said homogeneous powders mixture of a duration t p up to the uniaxial pressure of sintering. For example, before the first phase of temperature rise, the process may comprise a uniaxial pressure rise phase of a duration t p of one minute at a temperature of 50 ° C., up to the uniaxial sintering pressure.
Dans un mode de mise en œuvre particulier, la température de frittage est comprise entre 1000 ° C et 1050 ° C.  In a particular embodiment, the sintering temperature is between 1000 ° C. and 1050 ° C.
Dans un mode de mise en œuvre particulier, la température de frittage est maintenue pendant une troisième durée t3 comprise entre une et dix minutes. In a particular embodiment, the sintering temperature is maintained for a third time t 3 of between one and ten minutes.
Dans un mode de mise en œuvre particulier, le procédé comprend après l'étape b/ de frittage, une phase de descente en température et en pression uniaxiale pendant une quatrième durée t4, jusqu'à température ambiante et pression uniaxiale nulle. Selon un exemple de réalisation particulier, la durée t4 est comprise entre une et dix minutes. De préférence, elle est de cinq minutes. La descente en température et en pression uniaxiale d'une telle quatrième durée t4 est préconisée pour accommoder les contraintes dans la céramique et ainsi limiter les risques de fissuration. In a particular embodiment, the process comprises, after step b / of sintering, a phase of descent in temperature and uniaxial pressure for a fourth time t 4 , up to room temperature and zero uniaxial pressure. According to a particular embodiment, the duration t 4 is between one and ten minutes. Preferably, it is five minutes. The descent in temperature and uniaxial pressure of such a fourth time t 4 is recommended to accommodate the stresses in the ceramic and thus limit the risk of cracking.
Dans un mode de mise en œuvre particulier, la première durée ti est comprise entre cinq et dix minutes, et la deuxième durée t2 est comprise entre une et trois minutes. In a particular mode of implementation, the first duration ti is between five and ten minutes, and the second duration t 2 is between one and three minutes.
Dans un mode de mise en œuvre particulier, la première durée ti est de neuf minutes, la deuxième durée t2 est de deux minutes, la température de frittage est de 1050°C, la pression uniaxiale de fiittage est de 100 MPa et la troisième durée t3 est de cinq minutes. In a particular embodiment, the first duration ti is nine minutes, the second duration t 2 is two minutes, the sintering temperature is 1050 ° C, the uniaxial sintering pressure is 100 MPa and the third duration t 3 is five minutes.
Dans un mode de mise en œuvre particulier, la première vitesse A est supérieure à 10° C/min et inférieure ou égale à 200Ό/ιτιίη, de préférence supérieure à 50° C/min et inférieure ou égale à 150Ό/ιτιίη, encore préférentiellement supérieure à 90° C/min et inférieure ou égale à 120° C/min. Dans un mode de réalisation la deuxième vitesse B est supérieure ou égale à 10°C/min et inférieure à 200° C/min, de préférence Eipérieure ou égale à 50°C/min et inférieure à 150°C/min, encore préférertiellement supérieure ou égale à 90°C/min et inférieure à 120°C/min. In a particular mode of implementation, the first speed A is greater than 10 ° C / min and less than or equal to 200Ό / ιτιίη, preferably greater than 50 ° C / min and less than or equal to 150Ό / ιτιίη, more preferably greater than 90 ° C / min and less than or equal to 120 ° C / min. In one embodiment the second speed B is greater than or equal to 10 ° C / min and less than 200 ° C / min, preferably Eiior or equal to 50 ° C / min and less than 150 ° C / min, more preferably greater than or equal to 90 ° C / min and less than 120 ° C / min.
Dans un mode de réalisation particulier, la première vitesse A est de 100°C/min et la deuxième vitesse B est de 50°C/min.  In a particular embodiment, the first speed A is 100 ° C / min and the second speed B is 50 ° C / min.
Dans un mode de mise en œuvre particulier, la céramique est choisie parmi la zircone, l'alumine et un mélange de zircone et alumine.  In a particular embodiment, the ceramic is selected from zirconia, alumina and a mixture of zirconia and alumina.
Dans un mode de réalisation particulier la céramique est de la zircone renforcée à l'alumine (ATZ ou « Alumine Toughened Zirconia » en terminologie anglo-saxonne).  In a particular embodiment, the ceramic is zirconia reinforced with alumina (ATZ or "Alumina Toughened Zirconia" in English terminology).
Dans un mode de mise en œuvre particulier, le mélange de poudres comprend un pourcentage massique de pigment Sulfure de Cérium compris entre 1 % et 20%, de préférence entre 5% et 20%.  In a particular embodiment, the powder mixture comprises a weight percentage of cerium sulphide pigment of between 1% and 20%, preferably between 5% and 20%.
Dans un mode de réalisation particulier, le mélange de poudres comprend un pourcentage massique de pigment Sulfure de Cérium égal à 5%, 10% ou 20%.  In a particular embodiment, the powder mixture comprises a mass percentage of cerium sulphide pigment equal to 5%, 10% or 20%.
Dans un mode de mise en œuvre particulier il est adjoint des ajouts de frittage, tels que de l'AI203, Ti02, Y2O3, MgO, CaO, Ce02, ... aux poudres durant l'étape a/ de mélange pour améliorer la frittabilité du mélange de poudres et/ou les propriétés mécaniques du produit en matériau céramique obtenu par le procédé objet de la présente invention. In a particular embodiment, sinter additions, such as Al 2 O 3 , TiO 2 , Y 2 O 3 , MgO, CaO, CeO 2 , etc., are added to the powders during step a / of mixture for improving the sinterability of the powder mixture and / or the mechanical properties of the ceramic material product obtained by the process object of the present invention.
Selon un deuxième aspect, la présente invention vise un matériau céramique de couleur rouge homogène obtenu par le procédé objet de la présente invention, ledit matériau céramique comportant une céramique choisie parmi la zircone, l'alumine et un mélange de zircone et d'alumine, et comportant en outre un pigment de Sulfure de Cérium, la colorimétrie du matériau céramique étant comprise entre 30 et 65 pour le paramètre L, de préférence entre 30 et 60 pour le paramètre L, entre 10 et 40 pour le paramètre a, et entre 0 et 35 pour le paramètre b, de préférence entre 0 et 20 pour le paramètre b, selon le système L*a*b* de la Commission internationale de l'éclairage, la dureté du matériau céramique étant comprise entre 1000 et 1500 Hv, de préférence entre 1200 et 1500 Hv, et la ténacité du matériau céramique étant comprise entre 4 et 10 MPa.m1/2. According to a second aspect, the present invention aims at a homogeneous red-colored ceramic material obtained by the method which is the subject of the present invention, said ceramic material comprising a ceramic chosen from zirconia, alumina and a mixture of zirconia and alumina. and further comprising a cerium sulphide pigment, the colorimetry of the ceramic material being between 30 and 65 for the parameter L, preferably between 30 and 60 for the parameter L, between 10 and 40 for the parameter a, and between 0 and 35 for the parameter b, preferably between 0 and 20 for the parameter b, according to the system L * a * b * of the International Commission on Illumination, the hardness of the ceramic material being between 1000 and 1500 Hv, preferably between 1200 and 1500 Hv, and the toughness of the ceramic material being between 4 and 10 MPa.m 1/2 .
Une telle couleur rouge avec de telles propriétés de dureté et de ténacité n'avait jamais été atteinte auparavant pour des matériaux céramiques.  Such a red color with such hardness and toughness properties had never been achieved before for ceramic materials.
Enfin, selon un dernier aspect, la présente invention vise un produit du domaine de la bijouterie, de l'horlogerie ou de la joaillerie, comportant un matériau céramique de couleur rouge homogène obtenu par un procédé objet de la présente invention.  Finally, according to a last aspect, the present invention relates to a product of the field of jewelery, watchmaking or jewelery, comprising a homogeneous red-colored ceramic material obtained by a method that is the subject of the present invention.
Présentation des figures Presentation of figures
L'invention sera mieux comprise à la lecture de la description suivante, donnée à titre d'exemple nullement limitatif, et faite en se référant aux figures qui représentent :  The invention will be better understood on reading the following description, given by way of non-limiting example, and with reference to the figures which represent:
- Figure 1 : Variation du paramètre température (1 A) et du paramètre pression uniaxiale (1 B) dans le temps suivant un mode de mise en en œuvre du procédé objet de l'invention.  FIG. 1: Variation of the temperature parameter (1 A) and of the uniaxial pressure parameter (1 B) in time according to an embodiment of the method which is the subject of the invention.
- Figure 2 : Image visualisée au microscope électronique à balayages (MEB) d'un matériau céramique rouge à base de zircone obtenu par un mode de mise en œuvre de procédé objet de la présente invention.  FIG. 2: Image visualized by an electron scanning microscope (SEM) of a red ceramic material based on zirconia obtained by an embodiment of the method that is the subject of the present invention.
- Figure 3 : Courbes d'évolution de la valeur des paramètres L*, a* et b* du matériau céramique obtenu par le procédé de la présente invention mis en œuvre avec de la zircone, réflexion spéculaire incluse (SCI ou « Specular Component Included » en terminologie anglo-saxonne), selon le système colorimétrique de la Commission Internationale de l'éclairage, en fonction du pourcentage massique de pigment Sulfure de Cérium présent dans le mélange de poudres homogène. FIG. 3: Evolution curves of the value of the parameters L * , a * and b * of the ceramic material obtained by the process of the present invention implemented with zirconia, specular reflection included (SCI or "Specular Component Included") "In English terminology), according to the colorimetric system of the International Commission on Illumination, as a function of the mass percentage of cerium sulphide pigment present in the homogeneous powder mixture.
- Figure 4 : Image visualisée au MEB d'un matériau céramique à base d'ATZ obtenu par un mode de mise en œuvre du procédé objet de la présente invention. Description détaillée de l'invention FIG. 4: SEM visualized image of a ceramic material based on ATZ obtained by an embodiment of the method that is the subject of the present invention. Detailed description of the invention
On note dès à présent que les figures ne sont pas à l'échelle.  It is already noted that the figures are not to scale.
De manière plus générale, la portée de la présente invention ne se limite pas aux modes de mise en œuvre et de réalisation décrits ci-dessus à titre d'exemples non limitatifs, mais s'étend au contraire à toutes les modifications à la portée de l'homme de l'art. Chaque caractéristique d'un mode de réalisation peut être mise en œuvre isolément ou combinée à toute autre caractéristique de tout autre mode de réalisation de manière avantageuse.  More generally, the scope of the present invention is not limited to the embodiments and embodiments described above by way of non-limiting examples, but on the contrary extends to all modifications within the scope of the present invention. the skilled person. Each feature of one embodiment may be implemented in isolation or in combination with any other feature of any other embodiment in an advantageous manner.
La présente invention vise selon un premier aspect un procédé de fabrication d'un produit en matériau céramique comportant les étapes suivantes de :  The present invention aims according to a first aspect a method of manufacturing a ceramic material product comprising the following steps of:
a/- mélange d'une poudre céramique avec une poudre de pigment Sulfure de Cérium de sorte à obtenir un mélange de poudres homogène ;  a / - mixing a ceramic powder with a powder of cerium sulphide pigment so as to obtain a homogeneous powder mixture;
b/- frittage flash par chauffage par impulsions de courant électrique du mélange de poudres homogène sous vide pour densifier ledit mélange, ledit frittage étant réalisé à une température dite de frittage prédéterminée comprise entre 950 °C et 1 150° C et conportant une étape préalable b-i/ de chauffage dudit mélange de poudres homogène suivant un profil de température comprenant :  b / - flash sintering by electric current pulse heating of the homogeneous powder mixture under vacuum to densify said mixture, said sintering being carried out at a predetermined sintering temperature of between 950 ° C. and 1150 ° C. and having a prior step bi / heating said homogeneous powder mixture according to a temperature profile comprising:
o une première phase de montée en température à une première vitesse A pendant une première durée t-i , o et une deuxième phase de montée en température à une deuxième vitesse B inférieure à la première vitesse A pendant une deuxième durée t2, jusqu'à atteindre la température de frittage. o a first phase of temperature rise at a first speed A during a first duration ti, o and a second phase of temperature rise at a second speed B lower than the first speed A for a second duration t 2 , until reaching the sintering temperature.
Le mélange de poudres doit être homogène, c'est-à-dire que la répartition des grains de poudre de pigment Sulfure de Cérium parmi les grains de poudre de céramique doit être homogène. Une telle homogénéité du mélange peut par exemple être obtenue par la mise en œuvre de l'étape a/ de mélange de la poudre céramique avec la poudre de pigment de Sulfure de Cérium pendant une durée d'au moins deux heures. Le mélange peut être réalisé à sec dans un mélangeur tel qu'un Turbula®, en voie humide par attrition ou par voie chimique. The powder mixture should be homogeneous, that is, the grain distribution of Cerium Sulfide pigment powder among the ceramic powder grains should be homogeneous. Such homogeneity of the mixture may for example be obtained by the implementation of step a / of mixing the ceramic powder with the sulphide pigment powder. Cerium for a period of at least two hours. The mixture can be made dry in a mixer such as a Turbula®, wet attrition or chemical.
L'étape b/ de frittage flash comprend l'application sur ledit mélange de poudres homogène d'une pression uniaxiale dite de frittage prédéterminée.  Step b / flash sintering comprises applying to said homogeneous powder mixture a uniaxial pressure called sintering predetermined.
Dans le mode de réalisation particulier illustré en figure 1 , l'étape b/ de frittage flash du mélange de poudres se fait à une pression uniaxiale de frittage de 100 MPa (figure 1 B) et une température de frittage de 1050°C (figure 1 A).  In the particular embodiment illustrated in FIG. 1, the flash sintering step b / of the powder mixture is at a uniaxial sintering pressure of 100 MPa (FIG. 1B) and a sintering temperature of 1050 ° C. (FIG. 1 A).
Le procédé comprend avant et/ou pendant l'étape préalable b-i/, une phase de montée en pression uniaxiale sur le mélange de poudres homogène d'une durée tp d'une minute jusqu'à la pression uniaxiale de frittage 100 MPa. Cette montée en pression uniaxiale s'effectue à une température de 50 °C dans ce mode de réalisation. The process comprises before and / or during the prior step bi /, a uniaxial pressure increase phase on the homogeneous powders mixture with a duration t p of one minute up to the uniaxial sintering pressure 100 MPa. This uniaxial pressure increase is carried out at a temperature of 50 ° C. in this embodiment.
On observe également dans ce mode de réalisation illustré en figure 1 , une première phase de montée en température effectuée par impulsions de courant électrique à une première vitesse A de 100°C/min pendant une première durée ti de neuf minutes, et une deuxième phase de montée en température effectuée par impulsions de courant électrique à une deuxième vitesse B de 50° C/min pendant une deuxième durée de deux minutes. La température de frittage de 1050°C est atteinte en fn de deuxième phase et est maintenue pendant une troisième durée t3 de cinq minutes. Comme illustrée en figure 1 B, dans ce mode de réalisation la pression uniaxiale de frittage de 100 MPa est appliquée et maintenue durant la première, deuxième et troisième durée t-ι, t2 et t3, c'est-à-dire pendant le frittage flash comprenant la durée t3, mais également pendant l'étape préalable b-i/ comprenant les durées ti et t2. Dans d'autres modes de réalisation particuliers, la pression uniaxiale de frittage est appliquée et maintenue seulement durant la durée t3, c'est-à-dire seulement durant le frittage flash mais pas pendant l'étape préalable b-i/. In this embodiment illustrated in FIG. 1, a first phase of temperature rise effected by pulses of electric current is also observed at a first speed A of 100 ° C./min for a first duration ti of nine minutes, and a second phase. temperature rise effected by pulses of electric current at a second speed B of 50 ° C / min for a second period of two minutes. The sintering temperature of 1050 ° C is reached in second phase fn and is maintained for a third time t 3 for five minutes. As illustrated in FIG. 1B, in this embodiment the uniaxial sintering pressure of 100 MPa is applied and maintained during the first, second and third periods t-ι, t 2 and t 3 , that is to say during the flash sintering comprising the duration t 3 , but also during the prior step bi / comprising the durations t 1 and t 2 . In other particular embodiments, the uniaxial sintering pressure is applied and maintained only during the time t 3 , i.e. only during flash sintering but not during the prior step bi /.
Le procédé comprend également après l'étape b/ de frittage flash, une phase de descente en température et en pression uniaxiale pendant une quatrième durée t4 de cinq minutes jusqu'à température ambiante et pression uniaxiale nulle. Le matériel utilisé pour réaliser le frittage flash est un appareil de frittage flash communément utilisé, comprenant une enceinte de frittage qui est sous vide, deux électrodes entre lesquelles est insérée une colonne en graphite contenant les outillages, lesdites électrodes permettant d'appliquer un courant électrique et les pistons une pression uniaxiale, à l'échantillon de mélange de poudres par l'intermédiaire des outillages. Le frittage flash étant bien connu de l'homme du métier, il apparaît évident pour ce dernier que les séries d'impulsions de courant électrique sont des séries d'impulsions de courant électrique continu. Les outillages sont réalisés en un matériau réfractaire et conducteur du courant électrique, ce matériau ayant un coefficient de dilatation inférieur à celui du matériau céramique que l'on cherche à obtenir par frittage flash. Les outillages ont également des parois internes délimitant une cavité de forme complémentaire de celle de la pièce à réaliser en matériau céramique. The method also includes after step b / flash sintering, a temperature descent phase and uniaxial pressure for a fourth time t 4 for five minutes to room temperature and zero uniaxial pressure. The equipment used for the flash sintering is a flash sintering apparatus commonly used, comprising a sintering chamber which is under vacuum, two electrodes between which is inserted a graphite column containing the tools, said electrodes for applying an electric current. and the pistons a uniaxial pressure, to the sample of powder mixture via the tools. Since flash sintering is well known to those skilled in the art, it is obvious to the skilled person that the sets of electric current pulses are series of pulses of direct electric current. The tools are made of a refractory material and conductor of the electric current, this material having a coefficient of expansion less than that of the ceramic material that is sought to obtain by flash sintering. The tools also have internal walls delimiting a cavity of complementary shape to that of the part to be made of ceramic material.
EXEMPLES EXAMPLES
Exemple 1 : Fabrication d'un matériau céramique rouge à base de zircone. Example 1: Manufacture of a red ceramic material based on zirconia.
La poudre céramique utilisée est de la poudre de zircone TZ3Y (zircone stabilisée 3% molaire d'yttrine). La taille des grains de la poudre de céramique est de 63± 8 nm. The ceramic powder used is zirconia powder TZ3Y (stabilized zirconia 3% molar yttrine). The grain size of the ceramic powder is 63 ± 8 nm.
La taille des grains de la poudre de Sulfure de Cérium est d'environ 200 nm ± 24 nm.  The grain size of the cerium sulphide powder is about 200 nm ± 24 nm.
Différents mélanges de ces deux poudres de quantité finale égale à 15 g, sont réalisés :  Different mixtures of these two powders with a final quantity of 15 g are produced:
- TZ3Y (contrôle) = Zircone TZ3Y + 0% massique de pigment Ce2S3 ;TZ3Y (control) = Zirconia TZ3Y + 0% by weight of pigment Ce 2 S 3 ;
- TZ3Y5 = Zircone TZ3Y + 5% massique de pigment Ce2S3 ; TZ3Y5 = Zirconia TZ3Y + 5% by weight of Ce 2 S 3 pigment;
- TZ3Y10 = Zircone TZ3Y + 10% massique de pigment Ce2S3 ; TZ3Y10 = Zirconia TZ3Y + 10% by mass of pigment Ce 2 S 3 ;
- TZ3Y20 = Zircone TZ3Y + 20% massique de pigment Ce2S3. - TZ3Y20 = Zirconia TZ3Y + 20% by mass of Ce 2 S 3 pigment.
Dans chaque mélange sont ajoutés 15 g de billes d'attrition. Chaque mélange de poudres est ensuite placé dans un mélangeur de type Turbula® pour être mélangé pendant deux heures, sans ajout de liant ou d'autres composés organiques. In each mixture are added 15 g of attrition beads. Each A mixture of powders is then placed in a Turbula® mixer to be mixed for two hours without the addition of binder or other organic compounds.
Après l'étape de mélange, chacun des mélanges de poudres est placé séparément dans une matrice en graphite chemisée d'une feuille de graphite souple (par exemple de type Papyex® du fabricant MERSEN) pour assurer le contact électrique lors du frittage flash.  After the mixing step, each of the powder mixtures is placed separately in a graphite matrix lined with a flexible graphite sheet (for example of the Papyex® type from the manufacturer MERSEN) to ensure electrical contact during flash sintering.
Pour éviter la pollution des mélanges de poudres par des résidus de feuilles de graphite souples, du graphite est déposé sous forme de spray à l'interface entre les pistons et les mélanges de poudres. L'objectif est de protéger l'outillage tout en limitant les réactions avec le mélange de poudres. Ce spray peut être à base de nitrure de bore.  In order to avoid the pollution of powder mixtures by residues of flexible graphite sheets, graphite is deposited in the form of a spray at the interface between the pistons and the powder mixtures. The objective is to protect the tools while limiting the reactions with the powder mixture. This spray can be based on boron nitride.
Chaque matrice de graphite comprenant un mélange de poudres est placée dans l'appareil de frittage flash et la densification par frittage flash est réalisée selon les conditions opératoires exposées en figure 1 :  Each graphite matrix comprising a mixture of powders is placed in the flash sintering apparatus and the densification by flash sintering is carried out according to the operating conditions shown in FIG. 1:
- montée en pression uniaxiale sur le mélange de poudres homogène d'une durée tp d'une minute jusqu'à la pression uniaxiale de frittage 100 MPa. Cette montée en pression uniaxiale s'effectue à une température de 50 ° C ; uniaxial pressure rise on the homogeneous powders mixture with a duration t p of one minute up to the uniaxial sintering pressure 100 MPa. This uniaxial pressure rise is carried out at a temperature of 50 ° C .;
- toujours à pression uniaxiale de 100 MPa, une première phase de montée en température est effectuée à une première vitesse A de 100° C/min pendant une première durée ¾ de neuf minutes, et une deuxième phase de montée en température est effectuée à une deuxième vitesse B de 50°C/min pendant une deuxième durée t2 de deux minutes ; still at uniaxial pressure of 100 MPa, a first temperature increase phase is carried out at a first speed A of 100 ° C./min for a first duration ¾ of nine minutes, and a second phase of temperature rise is carried out at a temperature of second speed B of 50 ° C / min for a second duration t 2 of two minutes;
- toujours à pression uniaxiale de 100 MPa, la température de frittage de 1050°C est atteinte en fin de deuxième phase et est maintenue pendant une troisième durée t3 de cinq minutes ; - Still at uniaxial pressure of 100 MPa, the sintering temperature of 1050 ° C is reached at the end of the second phase and is maintained for a third time t 3 of five minutes;
- descente en température et en pression uniaxiale pendant une quatrième durée t4 de cinq minutes jusqu'à température ambiante et pression uniaxiale nulle. lowering temperature and uniaxial pressure for a fourth time t 4 of five minutes to room temperature and zero uniaxial pressure.
Les différents matériaux céramiques obtenus sont alors polis à l'aide de cinq disques diamantés (grains 220, 500, 1200, 2000 et 4000) et d'un disque en feutre sur lequel une solution de silicate est déposée. L'ensemble de la feuille de graphite souple est enlevé grâce à une polisseuse automatique. Les matériaux céramiques obtenus sont examinés au microscope électronique à balayage. La figure 2 illustre une image visualisée au microscope électronique à balayage du matériau céramique rouge issue du mélange TZ3Y10. The different ceramic materials obtained are then polished using five diamond discs (grains 220, 500, 1200, 2000 and 4000) and a felt disc on which a silicate solution is deposited. The entire soft graphite sheet is removed with an automatic polisher. The ceramic materials obtained are examined under a scanning electron microscope. FIG. 2 illustrates an image visualized with a scanning electron microscope of the red ceramic material resulting from the TZ3Y10 mixture.
Tableau 1 : Évolution de la taille de grains après frittage flash pour le mélange de poudres TZ3Y10.  Table 1: Evolution of the grain size after flash sintering for the mixture of powders TZ3Y10.
On observe une légère croissance des grains mais qui restent de tailles nanométriques (Tableau 1 ). Les trois raisons importantes sont : la température de frittage qui est faible (inférieure à 1200° C), la pression uniaxiale appliquée lors du frittage qui abaisse les températures de réaction et la durée t3 de frittage de cinq minutes. There is a slight growth of the grains but which remain of nanometric sizes (Table 1). The three important reasons are: the sintering temperature which is low (below 1200 ° C), the uniaxial pressure applied during sintering which lowers the reaction temperatures and the sintering time t 3 by five minutes.
Tableau 2 : Caractérisations mécaniques des matériaux céramiques obtenus.  Table 2: Mechanical characterizations of the ceramic materials obtained.
Des analyses de densité par la méthode d'Archimède à l'aide d'une balance hydrostatique, de dureté Vickers, et de ténacité par micro-indentation Vickers ont montré que les matériaux céramiques obtenus selon le procédé de la présente invention présentent un taux de densification supérieur ou égal à 98%, une dureté comprise entre 1220 et 1490 Hv, et une ténacité comprise entre 4,5 et 6,8 MPa.m1/2 (Tableau 2). L'évolution des paramètres de colorimétrie L*, a* et b* des matériaux céramiques obtenus par le procédé de la présente invention mis en œuvre avec de la zircone, réflexion spéculaire incluse (SCI ou « Specular Comportent Included » en terminologie anglo- saxonne), selon le système colorimétrique de la Commission Internationale de l'éclairage, en fonction du pourcentage massique de pigment Sulfure de Cérium présent dans le mélange de poudres, est illustrée par les courbes en figure 3. Density analyzes by the Archimedes method using a hydrostatic balance, Vickers hardness, and Vickers micro-indentation toughness have shown that the ceramic materials obtained according to the method of the present invention has a densification ratio greater than or equal to 98%, a hardness of between 1220 and 1490 Hv, and a toughness of between 4.5 and 6.8 MPa.m 1/2 (Table 2). The evolution of the L * , a * and b * colorimetric parameters of the ceramic materials obtained by the process of the present invention implemented with zirconia, including specular reflection (SCI or "Specular Comportent Included" in Anglo-Saxon terminology). ), according to the colorimetric system of the International Commission on Illumination, as a function of the mass percentage of cerium sulphide pigment present in the mixture of powders, is illustrated by the curves in Figure 3.
On constate que pour le mélange de poudres TZ3Y5 on obtient une colorimétrie de paramètres L*a*b* de 48/9/5, pour le mélange de poudre TZ3Y10 on obtient une colorimétrie de paramètres L*a*b* de 49/20/1 1 et, pour le mélange de poudres TZ3Y20 on obtient une colorimétrie de paramètres L*a*b* de 50/25/12. La poudre de zircone TZ3Y seule donne un matériau dont la colorimétrie est de paramètres L*a*b* de 48/1 /0. It can be seen that for the mixture of powders TZ3Y5 a colorimetry of parameters L * a * b * of 48/9/5 is obtained, for the mixture of powder TZ3Y10 a colorimetry of parameters L * a * b * of 49/20 is obtained. / 1 1 and for the mixture of powders TZ3Y20 a colorimetry of L * a * b * parameters of 50/25/12 is obtained. Zirconia powder TZ3Y alone gives a material whose colorimetry is L * a * b * parameters of 48/1 / 0.
Exemple 2 : Fabrication d'un matériau céramique rouge à base de zircone renforcée à l'alumine. La poudre céramique utilisée est de la poudre de la zircone renforcée à l'alumine (ATZ-20/80, 150 nm alpha alumine/20 nm zircone stabilisée 2,5% molaire). La taille des grains de la poudre de céramique est comprise entre 80 μιτι à 100 μιτι. Example 2: Manufacture of a red ceramic material based on zirconia reinforced with alumina. The ceramic powder used is alumina-reinforced zirconia powder (ATZ-20/80, 150 nm alpha alumina / 20 nm stabilized zirconia 2.5 mol%). The grain size of the ceramic powder is between 80 μιτι and 100 μιτι.
La taille des grains de la poudre de Sulfure de Cérium est d'environ 200 nm ± 24 nm.  The grain size of the cerium sulphide powder is about 200 nm ± 24 nm.
Différents mélanges de ces deux poudres de quantité finale égale à 15 g, sont réalisés :  Different mixtures of these two powders with a final quantity of 15 g are produced:
- ATZ (contrôle) = ATZ + 0% massique de pigment Ce2S3 ; ATZ (control) = ATZ + 0% by weight of pigment Ce 2 S 3 ;
- ATZ10 = ATZ+ 10% massique de pigment Ce2S3 ; ATZ10 = ATZ + 10% by weight of Ce 2 S 3 pigment;
Dans chaque mélange sont ajoutés 15 g de billes d'attrition. Chaque mélange de poudres est ensuite placé dans un mélangeur de type Turbula® pour être mélangé pendant deux heures, sans ajout de liant ou d'autres composés organiques. In each mixture are added 15 g of attrition beads. Each A mixture of powders is then placed in a Turbula® mixer to be mixed for two hours without the addition of binder or other organic compounds.
Après l'étape de mélange, chacun des mélanges de poudres est placé séparément dans une matrice en graphite chemisée d'une feuille de graphite souple (par exemple de type Papyex® du fabricant MERSEN) pour assurer le contact électrique lors du frittage flash.  After the mixing step, each of the powder mixtures is placed separately in a graphite matrix lined with a flexible graphite sheet (for example of the Papyex® type from the manufacturer MERSEN) to ensure electrical contact during flash sintering.
Comme dans l'exemple 1 , du graphite est déposé sous forme de spray à l'interface entre les pistons et les mélanges de poudres.  As in Example 1, graphite is deposited in the form of a spray at the interface between the pistons and the powder mixtures.
Chaque matrice de graphite comprenant un mélange de poudres est placée dans l'appareil de frittage flash et la densification par frittage flash est réalisée dans les conditions opératoires exposées en figure 1 et citées dans l'exemple 1 .  Each graphite matrix comprising a mixture of powders is placed in the flash sintering apparatus and the densification by flash sintering is carried out under the operating conditions described in FIG. 1 and cited in example 1.
Les différents matériaux céramiques obtenus sont alors polis de la même manière qu'exposé en exemple 1 . L'ensemble de la feuille de graphite souple est aussi enlevé et les matériaux céramiques obtenus sont examinés au microscope électronique à balayages. La figure 4 illustre une image visualisée au microscope électronique à balayages du matériau céramique rouge issue du mélange ATZ10.  The various ceramic materials obtained are then polished in the same way as described in Example 1. The whole of the flexible graphite sheet is also removed and the ceramic materials obtained are examined under a scanning electron microscope. FIG. 4 illustrates a scanned electron microscope image of the red ceramic material from the ATZ10 mixture.
Tableau 3 : Évolution de la taille de grains après frittage flash pour le mélange de poudres ATZ10.  Table 3: Evolution of the grain size after flash sintering for the mixture of ATZ10 powders.
On observe une certaine croissance des grains de zircone (x7) mais qui restent de tailles submicroniques (Tableau 3). Some growth of the zirconia grains (x7) is observed but which remain of submicron sizes (Table 3).
Nomenclature Température de Taux de Dureté Dureté Ténacité frittage (°C) densification (Hv) (GPa) (MPa.ml/2) Nomenclature Hardness Ratio Hardness Hardness Sintering (° C) densification (Hv) (GPa) (MPa.ml/2)
(%) ATZ 1050 95 % 1391 13,64 ±0,53 / (%) ATZ 1050 95% 1391 13.64 ± 0.53 /
ATZ10 1050 98% 1442 14.14 ±0,27 7,43 ±0,66 ATZ10 1050 98% 1442 14.14 ± 0.27 7.43 ± 0.66
Tableau 4 : Caractérisations mécaniques des matériaux céramiques obtenus. Table 4: Mechanical characterizations of the ceramic materials obtained.
Les analyses de densité par la méthode d'Archimède à l'aide d'une balance hydrostatique, de dureté Vickers, et de ténacité par micro-indentation Vickers, ont montré que les matériaux céramiques obtenus selon le procédé de la présente invention présentent un taux de densification supérieur ou égal à 98%, une dureté proche de 1442 Hv, et une ténacité comprise entre 6 et 8 MPa.m1/2 (Tableau 4). Density analyzes by the Archimedes method using a hydrostatic balance, Vickers hardness, and Vickers micro-indentation toughness, have shown that the ceramic materials obtained according to the process of the present invention exhibit a high densification greater than or equal to 98%, a hardness close to 1442 Hv, and a toughness of between 6 and 8 MPa.m 1/2 (Table 4).
On constate que pour le mélange de poudres ATZ10 on obtient une colorimétrie de paramètres L*a*b* de 61 ,0/13,9/33,4. It is found that for the mixture of powders ATZ10 a colorimetry of parameters L * a * b * of 61.0 / 13.9 / 33.4 is obtained.
Exemple 3 : Fabrication d'un matériau céramique rouge à base d'alumine. Example 3: Manufacture of a red ceramic material based on alumina.
La poudre céramique utilisée est de la poudre d'alumine dont la taille des grains est d'environ 150nm. The ceramic powder used is alumina powder whose grain size is about 150 nm.
La taille des grains de la poudre de Sulfure de Cérium est d'environ The grain size of the Cerium Sulfide powder is about
200 nm. 200 nm.
Différents mélanges de ces deux poudres de quantité finale égale à 15 g, sont réalisés :  Different mixtures of these two powders with a final quantity of 15 g are produced:
- AA (contrôle) = Alumine + 0% massique de pigment Ce2S3 ;- AA (control) = Alumina + 0% by weight of pigment Ce 2 S 3 ;
- AA10 = Alumine + 10% massique de pigment Ce2S3 ; AA10 = Alumina + 10% by weight of Ce 2 S 3 pigment;
- AA20 = Alumine + 20% massique de pigment Ce2S3 ; - AA20 = Alumina + 20% by weight of pigment Ce 2 S 3 ;
Comme pour les exemples précédents, dans chaque mélange sont ajoutés 15 g de billes d'attrition. Chaque mélange de poudres est ensuite placé dans un mélangeur de type Turbula® pour être mélangé pendant deux heures, sans ajout de liant ou d'autres composés organiques. As for the previous examples, in each mixture are added 15 g of attrition beads. Each powder mixture is then placed in a Turbula® type mixer to be mixed for two hours without addition of binder or other organic compounds.
Après l'étape de mélange, chacun des mélanges de poudres est placé séparément dans une matrice en graphite chemisée d'une feuille de graphite souple (par exemple de type Papyex® du fabricant MERSEN) pour assurer le contact électrique lors du frittage flash. Du graphite est également déposé sous forme de spray à l'interface entre les pistons et les mélanges de poudres. After the mixing step, each of the powder mixtures is placed separately in a graphite matrix lined with a flexible graphite sheet (for example of Papyex® type MERSEN manufacturer) to ensure the electrical contact during flash sintering. Graphite is also deposited as a spray at the interface between the pistons and the powder mixtures.
Chaque matrice de graphite comprenant un mélange de poudres est placée dans l'appareil de frittage flash et un frittage flash est réalisé dans les conditions opératoires exposées en figure 1 et citées dans l'exemple 1 .  Each graphite matrix comprising a mixture of powders is placed in the flash sintering apparatus and flash sintering is carried out under the operating conditions described in FIG. 1 and cited in example 1.
On constate que pour le mélange de poudres AA10 et AA20 on obtient une colorimétrie de paramètres L*a*b* de 57,3/29,1 /26,5 et 50,1 /35,5/30,3 respectivement. It is found that for the mixture of powders AA10 and AA20 a colorimetry of parameters L * a * b * of 57.3 / 29.1 / 26.5 and 50.1 / 35.5 / 30.3 respectively is obtained.

Claims

REVENDICATIONS
Procédé de fabrication d'un produit en matériau céramique caractérisé en ce qu'il comporte les étapes suivantes de : A method of manufacturing a product made of ceramic material characterized in that it comprises the following steps of:
a/- mélange d'une poudre céramique avec une poudre de pigment Sulfure de Cérium de sorte à obtenir un mélange de poudres homogène ;  a / - mixing a ceramic powder with a powder of cerium sulphide pigment so as to obtain a homogeneous powder mixture;
b/- frittage flash par chauffage par impulsions de courant électrique du mélange de poudres homogène sous vide pour densifier ledit mélange, ledit frittage flash étant réalisé à une température dite de frittage prédéterminée comprise entre 950 °C et 1 150°C et comportant une étape préalable b-i/ de chauffage dudit mélange de poudres homogène suivant un profil de température comprenant :  b / - flash sintering by electric current pulse heating of the homogeneous powder mixture under vacuum to densify said mixture, said flash sintering being carried out at a predetermined sintering temperature of between 950 ° C. and 1150 ° C. and comprising a step prior to bi / heating said homogeneous powder mixture according to a temperature profile comprising:
o une première phase de montée en température à une première vitesse A pendant une première durée t-i , o et une deuxième phase de montée en température à une deuxième vitesse B inférieure à la première vitesse A pendant une deuxième durée t2, jusqu'à atteindre la température de frittage. o a first phase of temperature rise at a first speed A during a first duration ti, o and a second phase of temperature rise at a second speed B lower than the first speed A for a second duration t 2 , until reaching the sintering temperature.
Procédé de fabrication selon la revendication 1 , dans lequel l'étape b/ de frittage flash comprend l'application sur ledit mélange de poudres homogène d'une pression uniaxiale dite de frittage prédéterminée comprise entre 25 et 130 MPa, de préférence entre 50 et 100 MPa. The manufacturing method according to claim 1, wherein the flash sintering step b comprises applying to said homogeneous powders mixture a predetermined sintering uniaxial pressure of between 25 and 130 MPa, preferably between 50 and 100. MPa.
Procédé selon la revendication 2, comprenant avant et/ou pendant l'étape préalable b-i/, une phase de montée en pression uniaxiale appliquée sur ledit mélange de poudres homogène, d'une durée tp, jusqu'à la pression uniaxiale de frittage. A method according to claim 2, comprising before and / or during the prior step bi /, a uniaxial pressure rise phase applied to said homogeneous powder mixture, of a duration t p , up to the uniaxial sintering pressure.
Procédé selon l'une quelconque des revendications 1 à 3, dans lequel la température de frittage est comprise entre 1000°C et 1050°C. Procédé selon l'une quelconque des revendications 1 à 4, dans lequel la température de frittage est maintenue pendant une troisième durée t3 comprise entre une et dix minutes. Process according to any one of claims 1 to 3, wherein the sintering temperature is between 1000 ° C and 1050 ° C. Process according to any one of claims 1 to 4, wherein the sintering temperature is maintained for a third time t 3 of between one and ten minutes.
Procédé selon l'une quelconque des revendications 1 à 5, comprenant après l'étape b/ de frittage, une phase de descente en température et en pression uniaxiale jusqu'à température ambiante et pression uniaxiale nulle, pendant une quatrième durée t4 comprise entre une et dix minutes, de préférence étant de cinq minutes. Process according to any one of Claims 1 to 5, comprising, after step b / of sintering, a phase of descent in temperature and in uniaxial pressure up to ambient temperature and zero uniaxial pressure, for a fourth duration t 4 lying between one and ten minutes, preferably five minutes.
Procédé selon l'une quelconque des revendications 1 à 6, dans lequel la première durée ti est comprise entre cinq et dix minutes, et la deuxième durée t2 est comprise entre une et trois minutes. A method as claimed in any one of claims 1 to 6, wherein the first duration t1 is between five and ten minutes, and the second duration t 2 is between one and three minutes.
Procédé de fabrication selon l'une quelconque des revendications 1 à 7, dans lequel la première vitesse A est de 100° C/minet la deuxième vitesse B est de 50°C/min. 9 - Procédé de fabrication selon l'une quelconque des revendications 1 à 8, dans lequel la céramique est choisie parmi la zircone, l'alumine et un mélange de zircone et alumine. A manufacturing method according to any one of claims 1 to 7, wherein the first speed A is 100 ° C / min and the second speed B is 50 ° C / min. 9 - The manufacturing method according to any one of claims 1 to 8, wherein the ceramic is selected from zirconia, alumina and a mixture of zirconia and alumina.
10 - Procédé selon la revendication 9, dans lequel la céramique est de la zircone renforcée à l'alumine (ATZ). 10 - Process according to claim 9, wherein the ceramic is zirconia reinforced with alumina (ATZ).
1 1 - Procédé de fabrication selon l'une quelconque des revendications 1 à 10, dans lequel le mélange de poudres comprend un pourcentage massique de pigment Sulfure de Cérium compris entre 1 % et 20%, de préférence entre 5 et 20%. 1 1 - Manufacturing process according to any one of claims 1 to 10, wherein the powder mixture comprises a weight percentage of cerium sulphide pigment of between 1% and 20%, preferably between 5 and 20%.
12 - Procédé de fabrication selon l'une quelconque des revendications 1 à 10, dans lequel le mélange de poudres comprend un pourcentage massique de pigment Sulfure de Cérium égal à 5%, 10% ou 20%. - Matériau céramique de couleur rouge homogène obtenu par un procédé selon l'une quelconque des revendications 1 à 12, comportant une céramique choisie parmi la zircone, l'alumine et un mélange de zircone et d'alumine, et comportant en outre un pigment de Sulfure de Cérium, la colorimétrie du matériau céramique étant comprise entre 30 et 65 pour le paramètre L, de préférence entre 30 et 60 pour le paramètre L, entre 10 et 40 pour le paramètre a, et entre 0 et 35 pour le paramètre b, de préférence entre 0 et 20 pour le paramètre b, selon le système L*a*b* de la Commission internationale de l'éclairage, la dureté du matériau étant comprise entre 1000 et 1500 Hv, de préférence entre 1200 et 1500 Hv, et la ténacité du matériau céramique étant comprise entre 4 et 10 MPa.m1/2. - Produit du domaine de la bijouterie, de l'horlogerie ou de la joaillerie comportant un matériau céramique de couleur rouge homogène obtenu par un procédé selon l'une quelconque des revendications 1 à 12. 12 - Manufacturing process according to any one of claims 1 to 10, wherein the powder mixture comprises a mass percentage of Cerium Sulfide pigment equal to 5%, 10% or 20%. Homogeneous red ceramic material obtained by a process according to any one of claims 1 to 12, comprising a ceramic selected from zirconia, alumina and a mixture of zirconia and alumina, and further comprising a pigment of Cerium sulphide, the colorimetry of the ceramic material being between 30 and 65 for the parameter L, preferably between 30 and 60 for the parameter L, between 10 and 40 for the parameter a, and between 0 and 35 for the parameter b, preferably between 0 and 20 for the parameter b, according to the system L * a * b * of the International Commission on Illumination, the hardness of the material being between 1000 and 1500 Hv, preferably between 1200 and 1500 Hv, and the toughness of the ceramic material being between 4 and 10 MPa.m 1/2 . - Product of the field of jewelery, watchmaking or jewelery comprising a homogeneous red ceramic material obtained by a process according to any one of claims 1 to 12.
EP17825576.6A 2016-12-20 2017-12-14 Method for manufacturing a red ceramic material Active EP3558893B1 (en)

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FR1662951A FR3060556B1 (en) 2016-12-20 2016-12-20 PROCESS FOR MANUFACTURING A RED COLORED CERAMIC MATERIAL
PCT/FR2017/053590 WO2018115649A1 (en) 2016-12-20 2017-12-14 Method for manufacturing a red ceramic material

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FR3082765B1 (en) * 2018-06-25 2021-04-30 Safran Aircraft Engines PROCESS FOR MANUFACTURING AN ABRADABLE LAYER
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CN110294629B (en) * 2019-08-15 2021-09-03 内蒙古科技大学 Lanthanum chromate ceramic and preparation method thereof
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